This invention relates to a relatively simple and inexpensive instrument for surgical stapling.
A variety of surgical staplers are known in which stapling is carried out at one end of the staplers in the space between their staple carrying parts and their anvils. See, for example, U.S. patent application, Ser. No. 967,421, filed Dec. 7, 1978, entitled "Instrument For Circuler Surgical Stapling Of Hollow Body Organs And Disposable Cartridge Therefor" (a division of which application issued as U.S. Pat. No. 4,304,236), in which a stapler has been described which can have a disposable cartridge assembly, containing surgical staples and a knife, and a cooperating anvil assembly mounted on its distal end before use and removed from it after use. In a stapler of this type, a knob or a wing nut has commonly been provided at the opposite end of the stapler. The knob or wing nut has been adapted to be turned to very significantly the space, between the staple carrying part and the anvil, in which a surgeon manipulates and positions body tissue to be stapled.
Typically, the maximum space between the staple carrying part and the anvil in such a stapler has been from approximately one-half inch to two inches. However, before tissue could be stapled with such a stapler, the space between its staple carrying part and its anvil has had to be reduced to a space that is compatible with the size of the staple being used. For example, when stapling with the common B-shape surgical staple, the space between the staple carrying part and the anvil has had to be reduced to between about 1 mm and 2.5 mm, so that tissue, compressed between the staple carrying part and the anvil, could be suitably fastened together with the stapler.
In order to provide a space between such a stapler's staple carrying part and its anvil that is compatible with the staple being used, so that suitable fastening of tissue can occur, means have been sought for assuring that the space between the staple carrying part and the anvil is suitable for fastening tissue. In pending U.S. patent application, Ser. No. 197,614, filed Oct. 16, 1980, entitled "Disposable Instrument For Surgical Fastening" (now U.S. Pat. No. 4,351,466), a stapler has been described that is provided with an indicator to show when the spacing between its staple carrying part and its anvil is within a range of spacings that is generally suitable for fastening tissue between the staple carrying part and the anvil (This range is hereinafter generally referred to as the "range of generally suitable spacings"). The indicator of that stapler has comprised the proximal end of a movable central rod, carrying the anvil, and the proximal end of a wing nut, threadedly engaged with the central rod. When the wing nut has been turned to move the central rod to a position in which the spacing between the anvil and the staple carrying part is within the range of generally suitable spacings (e.g., within the range of about 1 to 2.5 mm), the proximal end of the central rod has been either flush with, or has extended proximally of, the end of the wing nut.
However, with the stapler of application Ser. No. 197,614, it has not always been possible for a user of the stapler to quickly and accurately tell whether the spacing between its anvil and its staple carrying part has been within the range of generally suitable spacings. In this regard, when the spacing between the anvil and the staple carrying part has been close to the maximum spacing within the range of generally suitable spacings, it has been difficult or impossible to determine visually whether:
(a) the proximal end of the central rod is flush with or extends proximally of the end of the wing nut (i.e., the spacing between the anvil and staple carrying part is within the range of generally suitable spacings); or
(b) the proximal end of the central rod is located distally of the end of the wing nut (i.e., the spacing between the anvil and staple carrying part is not within the range of generally suitable spacings).
Thus, means have been sought for telling at a glance whether the spacing between an anvil and a staple carrying part in a surgical stapler is within the range of generally suitable spacings.